This invention relates to imaging of bodies and, more particularly, to an apparatus and method for generating image representations of a body. The invention has application to both animate and inanimate bodies.
There are many applications where it is useful to obtain an accurate three-dimensional image representation of a body. For example, in manufacturing or testing of objects having irregular shapes, it may be necessary or desirable to have information concerning one or more properties of the object: its surface shape, coordinates and area; the nature and shape of any of its cross-sections; and the volume it contains. Equipment for obtaining these properties tends to be complex and expensive, and often provides information that is incomplete and/or requires operator approximations and calculations.
In clinical applications, the task is further complicated by the inaccessibility, mechanical instability, and fragility of the organs to be imaged or measured. The human heart provides a difficult challenge in this regard.
Understanding the complex time-varying three-dimensional geometry and function of the heart has been the fundamental goal of cardiac imaging. Desirable techniques should be simple to use, safe, and inexpensive to meet the potentially vast clinical demand. Although magnetic resonance imaging and ultra-fast X-Ray computed tomography have the potential to provide precise 3D cardiac imaging, both are expensive and have limited availability. By contrast, monographic techniques including 2D real-time echocardiography are readily available, inexpensive, and pose no known risk to the patient. Despite these potential advantages, practical 3D echocardiography has been an elusive goal. This has been a consequence of both the rigorous demands of cardiac imaging and the difficulty of automating the image generation process, an essential requirement in a clinical setting. Prior investigators have reported techniques which permit a hand-held 2D sector transducer to be tracked in three dimensions. By recording these spatial data along with the 2D images and electrocardiogram, it has been possible to extract selected 2D planes, delineate their endocardial or epicardial contours, and derive an interpolated wire-frame surface in three-dimensions. However, because of the present inability to reliably perform endocardial edge detection by automated techniques, the requirement for antecedent edge detection of multiple selected 2D sections requires that an operator select a small subset of sectors in which hand-guided edge detection is carried out. The resultant 3D reconstruction reflects only the selected contours and is devoid of the rich anatomic detail intrinsic to the primary ultrasound backscatter data.
It is among the objects of the present invention to provide an apparatus and method for obtaining three dimensional image representations that overcome the difficulties and limitations of prior art techniques.